Effect of insemination regimen on embryo production in superovulated cows
Donaldson, L.E.
Veterinary Record 117(2): 35-37
1985
ISSN/ISBN: 0042-4900 PMID: 3929456 Document Number: 257462
Simmental, Holstein-Friesian and crossbred zebu cows were superovulated with 28 or 40 mg FSH administered over 4 days, and oestrus was synchronized with 65 mg PGF2 alpha on the 3rd day. The 3 experiments involved 112, 210 and 80 cows resp. Six insemination schemes were compared in which cows were inseminated 1-3 times 3, 12 and/or 24 h after detection of oestrus, using 1-3 "units" of semen. For cows inseminated 1, 2 and 3 times with 1 unit of semen, the number of fertilized ova recovered averaged 8.2, 6.3 and 9.1 resp., the total number of ova recovered 9.6, 8.9 and 13.2, and the number of transferable ova recovered 3.9, 3.9 and 6.8. For cows inseminated 1, 2 and 3 times and receiving 2 units of semen at the 1st or 2nd insemination, the number of fertilized ova recovered averaged 7.0, 7.4 and 8.6, and the number of transferable ova 3.8, 5.1 and 5.5. Differences between 1 and >1 insemination were significant for the last 2 traits. Two inseminations with 1 unit of semen was as effective as 2 inseminations with a total of 3 units in terms of the percentage of fertilized ova (68 and 70 resp.), av. number of fertilized ova recovered (10.3 and 8.3), av. number of embryos recovered (14.8 and 12.7), av. number of transferable embryos (6.7 and 5.7), and the percentage of transferable embryos (44 and 46). It was concluded that 1 insemination with a single unit of semen 12 h after the onset of oestrus gives satisfactory numbers of fertilized ova after the superovulation of donor cows.